It is well known that combustion engine emissions, such as those of motor vehicles, emit pollutants such as nitrogen oxide compounds (NOx), unburned hydrocarbons (CxHy) and carbon oxides (CO, CO2) from the combustion of such common fuels as gasoline and diesel. In the presence of sunlight, volatile organic compounds (VOCs) and NOx can join to form ozone, a main contributor to smog. Smog has been known to harm human health and have negative effects on the surrounding ecosystems and environment. Major smog occurrences are often linked to heavy motor vehicle traffic.
In recent decades, much attention has been given to reducing emissions of NOx, CxHy and COx. For example, catalytic converter devices containing surfaces coated with platinum, palladium, or rhodium are used in the exhaust system of motor vehicles, downstream from the combustion engine in an attempt to reduce pollutants (such as NOx, CxHy, and CO) to N2, O2, CO2 and H2O. However, some of the components of the catalytic converters are expensive. Additionally, not all of the pollutants are converted to less harmful bi-products, partly due to the fact that catalytic converters lose their efficiency over time.
In addition, those skilled in the art of photocatalytic coatings are familiar with titanium dioxide (TiO2) and aluminum oxide (Al2O3), in paint and coatings to break down viruses, mold, bacteria, odors and volatile organic compounds. For example, recent patents and patent applications discuss using TiO2 in attempts to reduce emissions (e.g., 6,122,909CA, 8,409,851B2 and EP 2721270 A1). It is also well known to those skilled in the art, that when certain photocatalysts, such as TiO2, Al2O3, WO3 and others are irradiated with light, the energy absorbed enables the production of hydroxyl radicals (−OH) to decompose potentially harmful compounds, as originally discovered by Japanese scientist Dr. Akira Fujishima in 1967, incorporated herein by reference (Fujishima, Akira; Honda, Kenichi (7 Jul. 1972). “Electrochemical Photolysis of Water at a Semiconductor Electrode”. Nature 238 (5358): 37-38)).
Energy from near ultraviolet light (potentially including wavelengths of up to 415 nm into the visible light range) allows for this photocatalytic reaction. For example, Chinese patent application number CN 201110105872 discusses using multiple ultraviolet (UV) lights inside of an automobile TiO2-coated exhaust chamber and TiO2-coated foam baffles and places the lights on sides the baffles of the exhaust chamber, which is also coated with TiO2, thereby requiring a specially manufactured exhaust system to replace an existing exhaust system and engine intake. This solution would be expensive to execute and therefore difficult for some consumers to implement, especially if a goal is to reduce vehicle emissions in an older vehicle or a “retrofit” of any combustion engine which could use an emissions-reducing method and device.
In addition, titanium dioxide is used most efficiently and economically applied uniformly across a specified surface area exposed to a light source emitting the required amount of energy. Moreover, insufficient illumination can substantially inhibit the formation of hydroxyl radicals production. Incorporating sufficient illumination into the photocatalytic device placed in line with the existing combustion engine exhaust system could be relatively easily retrofitted to existing systems to reduce pollutants emitted. A cost-efficient retrofit may further assist people and entities comply with various emissions standards and regulations.
What is needed is a method and device that is cost-effective and easily installed in any motor vehicle, existing combustion engine exhaust port, and other various burning and industrial processes that employ sufficient UV light to a photocatalytic compound. Such a method and device could be easily and quickly installed in many applications, such as with exhaust chambers of internal combustion engines as well as emissions from various manufacturing entities and other emissions sources, thus having a major impact on the health of humans, animals, and our planet.